package com.zhxh.nzpos.db;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Environment;
import android.util.Log;

public class DBHelper extends SQLiteOpenHelper {

	private final static String DB_NAME = "sell.sqlite";// 数据库名
	private final static int VERSION = 1;// 版本号
//	private final int BUFFER_SIZE = 400000;

	private final Context myContext;
	
	private SQLiteDatabase database;

	public static final String PACKAGE_NAME = "com.zhxh.nzpos";
	public static final String DB_PATH = "/data"
			+ Environment.getDataDirectory().getAbsolutePath() + "/"
			+ PACKAGE_NAME +"/databases";// 在手机里存放数据库的位置

	// 自带的构造方法
	public DBHelper(Context context, String name, CursorFactory factory,
			int version) {
		super(context, name, factory, version);
		this.myContext = context;
	}

	// 为了每次构造时不用传入dbName和版本号，自己得新定义一个构造方法
	public DBHelper(Context cxt) {
		this(cxt, DB_NAME, null, VERSION);// 调用上面的构造方法
		openDatabase();
	}

	public void openDatabase() {
		this.database = this.openDatabase(DB_PATH + "/" + DB_NAME);
	}

	// 版本变更时
	public DBHelper(Context cxt, int version) {
		this(cxt, DB_NAME, null, version);
	}

	private SQLiteDatabase openDatabase(String dbfile) {
		boolean dbExist = checkDataBase();

		if (dbExist) {
			Log.i("DBHelper. openDatabase ", "The database is there!");
			// do nothing - database already exist
/*			try {
				deleteDataBase();
				copyDataBase();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}*/
		} else {

			// By calling this method and empty database will be created into
			// the default system path
			// of your application so we are gonna be able to overwrite that
			// database with our database.
			this.getReadableDatabase();

			try {

				copyDataBase();

			} catch (IOException e) {

				throw new Error("Error copying database");

			}
		}
		return null;
	}

	public void closeDatabase() {
		this.database.close();
	}

	// 搜检数据库是否有效
	private boolean checkDataBase() {
		SQLiteDatabase checkDB = null;
		String myPath = DB_PATH + "/" + DB_NAME;
		try {
			checkDB = SQLiteDatabase.openDatabase(myPath, null,
					SQLiteDatabase.OPEN_READONLY);
		} catch (SQLiteException e) {
			// database does""t exist yet.
		}
		if (checkDB != null) {
			checkDB.close();
			System.out.println("");
		}
		return checkDB != null ? true : false;
	}
/**
 * copy database
 * @throws IOException
 */
	
	 private void copyDataBase() throws IOException{
		 
		//Open your local db as the input stream
		InputStream myInput = myContext.getAssets().open(DB_NAME);
		 
		// Path to the just created empty db
		String outFileName = DB_PATH + "/" + DB_NAME;
		 
		//Open the empty db as the output stream
		OutputStream myOutput = new FileOutputStream(outFileName);
		 
		//transfer bytes from the inputfile to the outputfile
		byte[] buffer = new byte[1024];
		int length;
		while ((length = myInput.read(buffer))>0){
		myOutput.write(buffer, 0, length);
		}
		 
		//Close the streams
		myOutput.flush();
		myOutput.close();
		myInput.close();
		 
		}
	 
	 /**
	  * delete database
	  * @throws IOException
	  */
	 private void deleteDataBase() throws IOException{
		 
		//Open your local db as the input stream
		InputStream myInput = myContext.getAssets().open(DB_NAME);
		 
		// Path to the just created empty db
		String outFileName = DB_PATH + "/" + DB_NAME;
		 
		//Open the empty db as the output stream
		OutputStream myOutput = new FileOutputStream(outFileName);
		 
		//transfer bytes from the inputfile to the outputfile
		byte[] buffer = new byte[1024];
		int length;
		while ((length = myInput.read(buffer))>0){
		myOutput.write(buffer, 0, length);
		}
		 
		//Close the streams
		myOutput.flush();
		myOutput.close();
		myInput.close();
		 
		}
/**
	 private void copyDataBase() throws IOException{
 
		//Open your local db as the input stream
		InputStream myInput = myContext.getAssets().open(DB_NAME);
		 
		// Path to the just created empty db
		String outFileName = DB_PATH + "/" + DB_NAME;
		 
		//Open the empty db as the output stream
		OutputStream myOutput = new FileOutputStream(outFileName);
		 
		//transfer bytes from the inputfile to the outputfile
		byte[] buffer = new byte[1024];
		int length;
		while ((length = myInput.read(buffer))>0){
		myOutput.write(buffer, 0, length);
		}
		 
		//Close the streams
		myOutput.flush();
		myOutput.close();
		myInput.close();
 
	}
*/
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onCreate(SQLiteDatabase arg0) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
		// TODO Auto-generated method stub

	}

}
